In a school class or a corporate meeting in which a projector that is a projection type display device is used, there is a case where a writing surface, such as a white board, on which a user can perform writing, is used as a projection surface, and where additional information, such as a character, is written on the projection surface in a state where an input image is projected onto the projection surface. In this case, the input image and the additional information are on the projection surface (writing surface). It should be noted that the input image means an image which includes an object, such as a symbol or a character, represented on a background of the image and which is used for presentations, or the like.
Patent Literature 1 describes an image projection device that records a projection surface on which an inputted image and additional information exist.
In the image projection device described in Patent Literature 1, a recorded image is generated in such a manner that the input image projected on the projection surface is photographed together with the additional information written on the projection surface.